The invention concerns a method for cross-referencing the identification of supports for tissue sample slices to be disposed thereon, with cross-reference to an identification information of a holder of an associated, not yet microtomised tissue sample.
The invention also concerns a device for carrying out such a method and a device for preparing to carry out the method to identify supports of tissue slices with cross-reference to identification information of a holder of a not yet microtomised tissue sample, wherein the holder is provided with an information carrier for cross-reference, and the device comprises a means for generating the identification information.
Examination of tissue samples from patients is a routine procedure in histological technology. The most common method consists of embedding the tissue samples in paraffin, slicing them with microtomes, staining them in a further process, covering them with a cover glass and supplying them to a microscope for diagnostic evaluation. In modern laboratories, the patient samples are automatically processed during the individual steps. The samples are initially prepared through the following steps: fixing, dehydration, clearing with an intermediate medium, and embedding in paraffin in an embedding device. Production of a paraffin block is realized in a pouring station. Cutting the paraffin block, with an embedded tissue sample, in a microtome, produces microscopic, thin slices. The thin slice thereby obtained is stained and contrasted in several steps in a staining device. After covering the thin slice with a cover glass on a cover glass covering device, the thin slice obtained from the patient sample is ready for evaluation under a microscope.
One problem consists in maintaining unique identification of the tissue samples to prevent confusion and loss of samples throughout all of the processing steps. Some progress has been achieved in this regard. In modern processing, immediately after slicing, the tissue sample is inserted into a so-called tissue cartridge, which is closed and secured by a lid. In addition to good liquid flow properties, modern tissue cartridges also offer distinct features to prevent loss of the sample and to provide unique identification. Towards this end, modern cartridges have a writing or printing surface of sufficient size and surface quality to permit writing or printing with sufficient adhesion and durability during subsequent processing. In this fashion, the sample can be clearly identified in the identified cartridge during embedding of the tissue. In the subsequent step, i.e. pouring the paraffin block around the tissue sample, the risk of sample confusion is still sufficiently prevented, since the same identified cartridge serves as support of the paraffin block with tissue sample, wherein the sample is connected to the identified cartridge via the solidified paraffin block.
In the next step, microscopic thin slices of the tissue sample are produced on a microtome. Towards this end, the paraffin block with embedded tissue sample and connected cartridge holder part are clamped into the sample holder of a microtome and sliced. Thin slices are thereby produced on the back of the microtome knife or on the edge of one-way blade holders, which are transferred manually, using a brush and tweezers, to a warm water bath for stretching the slices. The stretched, thin slices are then placed on a conventional, glass tissue slice support (slide). The labeling field of the sample slice support must now have the same allocating information concerning the tissue as is written on the tissue cartridge serving as the holder. Conventionally, several usable thin slices are produced from one tissue sample and are distributed on several tissue slice supports. This means that several tissue slice supports must contain the same identification as to origin of the tissue sample.
The tissue slice support can be labeled by handwriting as soon as the thin slices have been produced. The patient tissue information provided on the cartridges is thereby transferred onto one or more tissue slice supports through handwriting. Clearly, this method increases the danger of transfer errors and therefore offers little protection from confusion and errors. Additionally, the hand-written information must be read and further processed by other persons at a later time.
U.S. Pat. No. 4,276,253 discloses mounting an identification on the sample which is maintained for each sample tissue slice during cutting, i.e. is reproduced. There is no allocation problem since the tissue sample slice is already characterized during cutting. This requires extensive identification of samples using shaped, elongated labels, which are also cut. This requires an increase in size of the paraffin block being cut and also entails time-consuming embedding of these labels. The considerable technical effort is impractical.
Further documents (WO 00/62035, U.S. Pat. No. 5,854,075; U.S. Pat. No. 5,746,855 and DE 100 10 140 A1) describe automated processes, which eliminate allocation problems. Such full automation is problematic due to the extremely thin slices and can only be realized with considerable technical effort.
A method and devices of the above-mentioned type with manual cross-reference are also known, wherein one or more tissue slice supports are labeled with the same information at the same time when the tissue cartridge, which serves as a holder, is labeled at the start of the sample preparation process. This reduces the risk of confusion, in particular when the writing is carried out automatically with a coupled cartridge and tissue slice support printing system. This method is disadvantageous in that the previously labeled tissue slice supports cannot accompany the patient sample with tissue cartridge as one integrated unit in the subsequent steps. This means that, after slicing of a tissue sample, the matching previously labeled tissue slice supports must be located and identified through manual comparison of the written information. A further disadvantage is the fact that the number of tissue slice supports required for each tissue sample cannot be exactly predetermined at the time of labeling since, in addition to the specifications of the doctor, this number also depends on the assessment of the expert carrying out microtomisation. In practice, it is very difficult to adhere to a system, which ensures cross-reference of the tissue slice support, and tissue sample of the patient by allocating previously labeled tissue slice supports, since the samples must be relocated several times during the individual preparation steps. For this reason, the tissue slice support must disadvantageously be located in intermediate positions and comparative readings are required to provide a new cross-reference.
Pre-fabricated tissue slice supports with corresponding identification are difficult to allocate and would also have to be reproduced or be provided in excessive numbers when the expert providing the thin slices thereby realizes that more tissue sample slices are required than expected by the doctor. This problem increases when the tissue slice support identification must contain further information concerning different processing and evaluation, in addition to the cross-reference to the patient.
It is therefore the underlying purpose of the present invention to provide a safe and efficient identification method for tissue slice supports and provide devices therefor which simplify the described cross-referencing problems in histological technology occurring during manual cross-referencing.